Heat pump system and method for operating said system

Abstract

Methods and systems are provided for operating a climate control system. In one example, a method for operating a vehicle climate control system includes modeling a pressure in a heat pump downstream of an exterior heat exchanger an upstream of an expansion valve. The method also includes operating the expansion valve to cool a vehicle cabin using the modeled pressure in conjunction with a temperature from a sensor positioned upstream of the expansion valve and downstream of the exterior heat exchanger.

The invention claimed is: 
     
       1. A method for operating a vehicle climate control system, comprising: a controller, modeling a pressure in a heat pump circuit downstream of an exterior heat exchanger and upstream of an expansion valve; and operating the expansion valve in the heat pump circuit to cool a vehicle cabin based on the modeled pressure and a temperature from a sensor positioned upstream of the expansion valve and downstream of the exterior heat exchanger; wherein modeling the pressure in the heat pump circuit includes determining a pressure drop across the exterior heat exchanger using a pressure from a pressure sensor positioned upstream of the exterior heat exchanger, a speed of a compressor in the heat pump circuit, and/or an ambient temperature. 
     
     
       2. The method of  claim 1 , further comprising a refrigerant to coolant heat exchanger coupled to a cabin heating circuit and wherein the cabin heating circuit is shut-down during operation of the expansion valve. 
     
     
       3. The method of  claim 1 , wherein operating the expansion valve in the heat pump circuit occurs in a cooling mode of the vehicle climate control system and wherein the method further comprises transitioning the vehicle climate control system into the cooling mode from a heating mode responsive to receiving a cabin climate control adjustment request. 
     
     
       4. The method of  claim 1 , wherein operating the expansion valve includes increasing or decreasing a degree of opening of the expansion valve to increase or decrease an amount of refrigerant delivered to an evaporator. 
     
     
       5. The method of  claim 1 , further comprising operating the compressor in the heat pump circuit based on the modeled pressure. 
     
     
       6. The method of  claim 1 , wherein the expansion valve is a cooling expansion valve and wherein operating the cooling expansion valve in the heat pump circuit to cool the vehicle cabin includes operating the cooling expansion valve using a subcool value determined using the modeled pressure and a temperature from a temperature sensor downstream of the exterior heat exchanger. 
     
     
       7. A vehicle system comprising:
 an energy storage device configured to transfer energy to an electric motor configured to transfer motive power to a drive wheel; 
 a cabin heating circuit including:
 a cabin heat exchanger positioned downstream of a refrigerant to coolant heat exchanger in a heat pump circuit, the refrigerant to coolant heat exchanger transferring heat between a heat pump in the heat pump circuit and the cabin heating circuit, wherein the heat pump circuit is configured to receive energy from the energy storage device; and 
 an electrically operated heater positioned between the refrigerant to coolant heat exchanger and the cabin heat exchanger; and 
 
 a controller including instructions stored in memory that when executed cause the controller to:
 model a pressure in the heat pump circuit downstream of an exterior heat exchanger and upstream of a cooling expansion valve; and 
 in a cooling mode, operate the cooling expansion valve in the heat pump circuit to cool a vehicle cabin and/or a vehicle battery based on the modeled pressure and a temperature from a temperature sensor positioned upstream of the cooling expansion valve and downstream of the exterior heat exchanger. 
 
 
     
     
       8. The vehicle system of  claim 7 , wherein modeling the pressure in the heat pump circuit includes determining a pressure drop across the exterior heat exchanger using a pressure from a pressure sensor positioned directly downstream or upstream of the refrigerant to coolant heat exchanger and wherein the cabin heating circuit coupled to the refrigerant to coolant heat exchanger is shut-down during operation of the cooling expansion valve. 
     
     
       9. The vehicle system of  claim 7 , wherein the controller further comprises instructions stored in the memory that when executed cause the controller to:
 transition between a heating mode of the vehicle system to the cooling mode responsive to receiving a cabin climate control adjustment request. 
 
     
     
       10. The vehicle system of  claim 7 , wherein the refrigerant to coolant heat exchanger is a water cooled condenser. 
     
     
       11. The vehicle system of  claim 7 , wherein the vehicle system is included in a hybrid vehicle that includes an internal combustion engine. 
     
     
       12. The vehicle system of  claim 7 , wherein the vehicle system is included in a battery electric vehicle. 
     
     
       13. A method for operating a vehicle climate control system, comprising: a controller, modeling a pressure in a heat pump circuit downstream of an exterior heat exchanger and upstream of a cooling expansion valve based on a pressure from a pressure sensor positioned between a heating expansion valve and downstream of a water cooled condenser in the vehicle heat pump system; and in a cooling mode, adjusting an output of a cooling expansion valve the heat pump circuit to cool a vehicle cabin based on the modeled pressure and a temperature from a sensor positioned upstream of the cooling expansion valve and downstream of the exterior heat exchanger. 
     
     
       14. The method of  claim 13 , wherein the water cooled condenser is coupled to the heat pump circuit and a cabin heating circuit and wherein the cabin heating circuit is shut-down while the pressure in the heat pump circuit is modeled. 
     
     
       15. The method of  claim 13 , further comprising transitioning into the cooling mode from a heating mode of the vehicle climate control system responsive to receiving a cabin climate control adjustment request. 
     
     
       16. The method of  claim 13 , wherein in the cooling mode, refrigerant is transferred from the cooling expansion valve directly to an evaporator. 
     
     
       17. The method of  claim 13 , wherein operating the cooling expansion valve in the heat pump circuit to cool the vehicle cabin includes operating the cooling expansion valve using a subcool value determined using the modeled pressure and a temperature from a temperature sensor downstream of the exterior heat exchanger. 
     
     
       18. The method of  claim 13 , further comprising operating a compressor in the heat pump circuit based on the modeled pressure. 
     
     
       19. The method of  claim 13 , further comprising operating a heating expansion valve in the heat pump circuit based on the modeled pressure.